Problem: $ { {-4} \times \left[\begin{array}{rr}{4} & {0} \\ {-2} & {4}\end{array}\right] = {?} } $
To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{rr}{-4}\times{4} & {-4}\times{0} \\ {-4}\times{-2} & {-4}\times{4}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{-16} & {0} \\ {8} & {-16}\end{array}\right]}$